Presently, several devices to achieve a longitudinal spacing between transversal ranks of articles are known.
For instance, patent document IT-927.943 substantially discloses a closed loop conveyor, provided with thrust bars, orbiting in a vertical closed loop longitudinally extending upstream to downstream and surrounding the articles transport path. Thrust bars are driven at a constant speed and provide to route pre-formed groups of articles along a straight translation path comprising, arranged upstream to downstream: a first sliding surface, the upper branch of a closed path transport tape conveyor, and a second sliding surface, where the transport tape has a linear speed greater than that of the thrust bars.
When a group of articles is transferred by the thrust bars from the first sliding surface to the transport tape, transversal ranks of articles, because of the difference in longitudinal speed existing between bars and tape, are sequentially accelerated toward downstream with a speed equal to that of the tape, so achieving a longitudinal spacing between the transversal ranks of articles, that allows a partition element to be inserted between them.
Successively, the transversal ranks of articles are transferred via the transport tape to the second sliding surface, passing from the maximum speed down to zero speed, to be then accumulated on said second Sliding surface, consequently to the conveyance of the following transversal ranks, by means of the transport tape and the bar. Said bar, coming from the back, transports the group downstream for all further operation.
A first drawback of such a device is that the articles acceleration and deceleration, obtained by means of a force applied at their bottom end (the acceleration occurring on the transport tape and the deceleration on the second sliding surface), causes the article to upset, respectively in an upstream and downstream direction.
A further drawback is that during the deceleration phase occurring on said second sliding surface, the articles belonging to a group can violently bump one against the other and, although they are equipped with partition elements, this can damage or even break them, especially in the case where they are glass bottles or cans.
Moreover, it must be noted that, in order to reduce the occurrence of the above mentioned drawbacks, the device must slow down its operating speed, accordingly reducing its productive capacity.
A second device longitudinally spacing up transversal ranks of articles is described in patent document IT-1.543.364.
Said device substantially describes a sliding surface provided with longitudinal shims, on which a flow of transversely and longitudinally ranged articles is routed, and a plurality of a transversal rows of pegs, carried by respective transversal bars, said bars being supported by an underlying chain conveyor, having chains wrapping in a closed loop on respective parallel vertical planes. According to the device arrangement, said pegs follow a closed loop vertical orbit, whose upper branch acts in the operating area of the articles translating path.
The device operates by vertically inserting the pegs, from the bottom upwards, between the articles moving on the sliding surface. Near the downstream end of the chain conveyor, the upper end of said pegs is inclined downstream, providing for a slight spacing between the transversal article ranks.
That device has its drawback in achieving only a small longitudinal spacing between the transversal ranks, and only for a short while, so that the transversal partition element must be inserted in a very fast and accurate way.